Merge branch 'ab/make-optim-noop'

Makefile refactoring with a bit of suffixes rule stripping to
optimize the runtime overhead.

* ab/make-optim-noop:
  Makefiles: add and use wildcard "mkdir -p" template
  Makefile: add "$(QUIET)" boilerplate to shared.mak
  Makefile: move $(comma), $(empty) and $(space) to shared.mak
  Makefile: move ".SUFFIXES" rule to shared.mak
  Makefile: define $(LIB_H) in terms of $(FIND_SOURCE_FILES)
  Makefile: disable GNU make built-in wildcard rules
  Makefiles: add "shared.mak", move ".DELETE_ON_ERROR" to it
  scalar Makefile: use "The default target of..." pattern